If you're willing to try something from 1990, I suggest you try this one:

Living Game http://www.mangaupdates.com/series.html?id=1173A romantic comedy about Fuwa, a guy living in a small apartment in overcrowded Tokyo, who wants to have a place of his own. Because of a building accident in their new office building, Fuwa's company (5 employees) had to move into his apartment, right after he had moved to a larger place. And the new employee (Hiyama Izumi, a 15 year-old girl) had to move into Fuwa's place, as she had just come from the country. Then Fuwa's old girlfriend Tokiko, who had already gotten married, ran away from her husband and came to Fuwa's place.

One manga comes into my mind:Densha OtokoIt's based on a true story, and is about a geek who meets a beautiful woman. Comedy, mismatched couple, romance, seinen.This story became pretty famous in Japan.

How about Genshiken? It's a good one, about a college otaku entering a geeky club.

School romance:

I second Nana to Kaoru, but take into acount that it's really borderline H.

Horimiya A nice manga in which the boy and the girl have sides that don't show in class, but then they discover each others' secrets and develop an unexpected friendship.

Angel Densetsu A comedy in which the male protagonist is always misunterstood as a bad guy lol This is a good comedy with some romance.

And ...

Bakuman Good one with a good peek into the mangaka's lifes.Love Hina Ok, this is tagged as a Harem, and yes, it's a Harem, but it has nothing to do with ichigo 100%. The mc is not an unbeareable playboy.B Gata H Kei Beware, this one is 4-koma. Also, 100% comedy. Maybe too much comedy?

By the way, all of my suggestions are of mangas really diferent from each other.

@-shiratori-[/b] i'm not looking for borderline H per se, i'm merely suggesting that is would not be shunned if suggested.

Thanks everyone for the suggestions so far but I've yet to see anything that jumps at me.

maybe this might help A romance that deals with adults rather than teenagers, children or ridiculous age gaps that also has comedy if possible.

I see, but I suggest you still have a look at Yuria 100 Shiki. It's hilarious and the ecchi content is not so bad (it's heavily censored + basically all of the ecchi scenes are just used as initiation for gags). The romance is also quite good, although I have yet to see the ending. All in all, I'd suggest you give it a try.